Atmospheric nitrogen dioxide (NO 2) can be dry/wet deposited into plant leaves mainly through stomata, with a small fraction of cuticle deposition. Plants in nature present a wide variation in NO 2 assimilation and the resistance. The ability of leaf NO 2 uptake and efficient remobilization of NO 2-derived NO 3-/NO 2 is important for normal plant growth and to withstand nitrogen deprivation. Moreover, leaf-and root-derived NO 3 metabolisms have both links and differences. This review emphasizes on the fates of NO 2-drived NO 3-, including i) the assimilation into amino acids, ii) accumulation in vacuoles, and iii) reemission by NO x (NO and/or NO 2), and discuss metabolic differences of NO 2-drived and root-derived NO 3 . Special attention is drawn to NO x evolution in apoplast and symplast of leaves and its control to stomatal dynamics. Moreover, further progress is proposed to get a better understanding of the dynamic uptake of NO 2 and NO 3 transporters in leaves.